Add an option to allow developers to enable thread affinity of Netty if net.openhft.affinity is on classpath

[JamesChenX]

Motivation

1. Make full use of CPUs cache
2. Reduce context switching

Desired solution

Add an option to allow developers to enable thread affinity of Netty if net.openhft.affinity is on classpath

TcpServer.create()
	.host("localhost") 
	.port(8080)
	// .threadAffinity() // Something like this
	// .threadAffinity(false)
	.bindNow();

Reference: https://github.com/netty/netty/wiki/Thread-Affinity

Considered alternatives

No.

Additional context

No.

[violetagg]

@JamesChenX You should be able to use the current API

ThreadFactory threadFactory = new AffinityThreadFactory("atf_wrk", AffinityStrategies.DIFFERENT_CORE);
EventLoopGroup eventLoopGroup = new NioEventLoopGroup(10, threadFactory);

TcpServer.create()
	.host("localhost") 
	.port(8080)
	.runOn(eventLoopGroup)
	.bindNow();

https://projectreactor.io/docs/netty/release/api/reactor/netty/transport/Transport.html#runOn-io.netty.channel.EventLoopGroup-

[JamesChenX]

OK, it's fine for us to use the APIs, and I just wanted to confirm whether you will do it, so we don't reinvent the wheel. Thanks.

[JamesChenX]

@violetagg . One more enhancement point, we would like to specify the number of select (acceptor) threads and the number of workers while using thread affinity. But there is no way for that now, could you provide a method like .runOn(acceptorEventLoopGroup, workerEventLoopGroup)? So that we can use custom acceptor/worker EventLoopGroup with thread affinity enabled.

[violetagg]

@JamesChenX You can do it like this:

final int acceptorThreads = 1;
final int workerThreads = 10;
EventLoopGroup acceptorGroup = new NioEventLoopGroup(acceptorThreads);
ThreadFactory threadFactory = new AffinityThreadFactory("atf_wrk", AffinityStrategies.DIFFERENT_CORE);
EventLoopGroup workerGroup = new NioEventLoopGroup(workerThreads, threadFactory);

TcpServer.create()
	.host("localhost") 
	.port(8080)
        .runOn(new LoopResources() {
	         @Override
	         public EventLoopGroup onServer(boolean useNative) {
		         return workerGroup;
	         }

	         @Override
	         public EventLoopGroup onServerSelect(boolean useNative) {
		         return acceptorGroup;
	         }
         })
	.bindNow();

[JamesChenX]

@violetagg it can work but the code isn't that elegant compared to runOn(acceptorEventLoopGroup, workerEventLoopGroup). Anyway, thanks for your continuous support!